Combine the tomato sauce, browned beef, onion, garlic powder, oregano, pepper, and red pepper flakes in a large saucepan. Bring to a simmer and allow to simmer for 15 minutes. Ladle some of the meat sauce into the bottom of your slow cooker.

Combine the cottage cheese and egg and layer in first with 1) cabbage 2) meat sauce 3) cottage cheese and 4) mozzarella. Layer a few times being sure to end with the mozzarella cheese.